Fuel injection idle enrichment control mechanism



Sept. 22, 1964 J. M. wHALEN FUEL. INJECTION IDLE ENRICHMENT CONTROL MECHANISM AFiled neo. 19, 1960 au. va 7ans-wr frzvefzZr.' kan Zl/alen @y @e7/w United States Patent O 3,149,619 FUEL INJECTION IDLE ENRICHMENT CNTROL NECHANISM .lohn M. Whalen, Decatur, Ill., assigner to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Filed Dec. 19, 1960, Ser. No. '76,758 3 Claims. (Cl. 123-140) This invention relates to an idle control mechanism for a fuel injection system that is adapted to enrich or increase the output of a fuel injection pump during idle condition of the engine.

In the conventional internal combustion engine, it is necessary to enrich the fuel supplied during idle conditions primarily to compensate for exhaust gas dilution. This enrichment is necessary on carbureted engines as well as on engines equipped with fuel injection systems. The effect of exhaust gas dilution is as follows:

When the engine is operated at idle condition, the throttle valve is almost completely closed, and the pressure within the air-intake manifold is much lower than atmospheric pressure. The pressure within a combustion chamber or cylinder during an exhaust stroke, however, is close to atmospheric pressure. When the air-intake valve opens, a portion of the exhaust gas remaining in the cylinder expands into the air-intake manifold. During the remainder of the intake stroke, the exhaust gas is sucked back into the combustion chamber before a mixture of fresh air and fuel enters the chamber. The fuel-to-air ratio supplied under this condition must be increased or enriched to offset the eects of the inert exhaust gas which dilutes the explosive mixture. The amount of enrichment necessary is a function of idle speed and valve overlap. When the throttle valve is opened, the pressure within the air-intake manifold rises and the effect of exhaust gas dilution is diminished. The proportion of fuel supplied thereafter should be decreased to maintain the proper air-to-fuel ratio.

It is an objectof the present invention to provide a control system for a fuel injection pump, including a mechanism responsive to throttle condition for delivering a metering bias force to the system during idle or closed throttle condition.

It is a more particular object to provide a control system adapted to control the output of a fuel injection pump, including a manifold pressure responsive control means for controlling the output of the pump, and an adjustable idle enrichment control means for exerting' a bias force on the manifold pressure responsive servornotor during idle or closed throttle condition.

It is a still more particular object to provide a control mechanism for a fuel injection pump, including a movable cam adapted to control the output of the pump, a manifold pressure responsive control means having a exible diaphragm for moving the cam, and an idle enrichment control means having a flexible diaphragm and an adjustable plunger eifective to exert a bias force on the cam, the diaphragm of said idle enrichment control means being responsive to a diiierential in pressure between atmospheric pressure and manifold pressure during closed throttle condition, and being inoperative during open throttle condition.

The invention consists of the novel constructions, arrangements, and devices to be hereinafter described and claimed for carrying out the above-stated objects and y such other objects as will appear from the following description of a preferred form of the invention, illustrated with reference to the accompanying drawings, wherein: FIG. l is a schematic view, partially in section, of the improved control mechanism of the present invention; FIG. 2 is an enlarged sectional view of a portion of the control mechanism of FIG. l;

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FIG. 3 is a view taken on line 3-3 of FIG. 2; and FIG. 4 is a graph of the air-fuel ratio demand of an internal combustion engine as a function of throttle opening.

Description Referring to FIG. 1, the complete control mechanism is designated generally by the numeral 10 and is adapted to control the output of a fuel injection pump 11. The mechanism 10 comprises a computer or integrator section 12, a manifold pressure responsive control means 13, an idle enrichment control means 14 and a throttle body 15.

The fuel injection pump 11 includes a metering valve or shuttle valve 16 for metering the size of fuel charges delivered by the pump 11. The pump 11 is driven in a timed relationship with the engine cam shaft by any suitable means (not shown). The total fuel output of the pump increases directly with engine speed, but the size of the charges delivered to the engine cylinders depends upon operating conditions. The fuel output hereinafter referred to will be the charge size.

The computer section 12 comprises a casing 19 attached to the pump 11, a movable cam 20 having a cam surface 21, a cam follower 22 in contact with the cam surface 21, and a cam follower arm 23 carrying the follower 22. The cam 20 is attached to a connecting shaft 24 of the manifold pressure responsive control means 13. The cam follower or roller 22 is rotatably mounted on a pin 25 carried by the arm 23, and the arm 23 is pivotally disposed on a pin 26 mounted in the casing 19. A connecting link 27 is disposed between the cam follower arm 23 and the metering valve 16 of the pump 11. The link 27 is moved longitudinally by the cam follower arm 23 for controlling the output of the pump 11 as the cam 20 is moved longitudinally under the influence of the control means 13.

v The manifold pressure responsive control means 13 comprises a casing 30 formed with an internal chamber or cavity 31, a liexible diaphragm 32, a spring retaining cup 33, and a spring 34. The spring retaining cup 33 and diaphragm 32 are attached to connecting shaft 24 by means of a screw 35. The casing 30 is attached to the casing 19 and is formed with a port 36 opening into the chamber 31. The port 36 is connected by means of a conduit 37 to a port 3S in the air-intake manifold 39.

The idle enrichment control 'means 14 comprises a casing 40 formed with an internal chamber or cavity 41, a flexible diaphragm 42 and an adjustable plunger 43 carried by theilexible diaphragm 42. The diaphragm 42 is sandwiched between the casings 30 and 40 which are fastened together by a plurality of machinescrews 44. The plunger 43 extends through an opening 45 formed in the wall of the casingt) and is adaptedto contact the head of the screw 35 for exerting a force on the connecting shaft 24 and cam 20. The casing 40 is formed with a port 46 opening into the cavity 41 and this port is connected by' means of a conduit 47 to aport 48 formed in the throttle body 15. Y

Referring to FIG. 2, an enlarged sectional view of a portion of the idle enrichment control means 14 is shown. The plunger 43 is carried by a sleeve 49 which is attached to the diaphragm 42 by means of a nut 5t). The sleeve 49 is formed with a central cylindrical bore 51 through which theY plunger 43 extends. The sleeve 49 is formed with a circular flange 52 which is adapted to abut against a shoulder 53 formed in the casing 30. The plunger 43 is formed with external'threads 54 and an end slot S5 The initial position of the plunger 43 with respect to the screw 35 is set by means of an adjusting nut 56 threaded on the threads 54. This position is locked by means of ya locking nut S7.

` The plunger 43 is also formed with a longitudinal flat or keyway 58 throughout a portion of its length and with external threads 59. A detent collar 66 is keyed to the plunger 43 and is adapted to slide longitudinally along the Vkeyway 58. A threaded collar 61 is threaded on threads 59 on the end of the plunger 43 adjacent the head of screw 35, and a spring 62 surrounds the plunger 43 and is disposed under compression between the threaded collar 61 and the detent collar 69. Thel collar 61 is formed with a slot 63 for receiving one end of the spring 62, and the flange 52 is formed with 'a slot 64 for receiving the other end of the spring 62. The detent collar 60 is formed with apluralityof depressions 65 on one side thereof which coact with a detent ball 66 for releasably holding the collar 60 in any one of a plurality of positions.

Once 'the initial position of the plunger 43 has been set with respect to the screw 35 by means of the adjusting nut 56, the magnitude of the idle bias force is obtained by adjusting the compression of the spring 62. The calibration of the idle bias for is obtained by inserting a screwdriver in the slot 55 and turning the plunger 43 within the collar 61. Since the spring 62 is anchored at one end to the collar 61, turning the plunger 43 causes the collar 61 to move longitudinally along the lthreads 59 for either increasing or decreasing the compression of the spring 62. The detent collar 6i) is turned with the plunger 43 andthe compression of the spring 62 tends to force the collar 6i) axially to the left, as shown. The plunger 43 and collar 60 are turned until the desired compression of the spring 62 is obtained and the ball 66 rests in one of the depressions 65 formed in the collar 6%. The detent ball 66 functions to hold the calibration of the spring 62 unless or until this adjustment is changed by manual operation.

The elfective area 'of the diaphragm 42 preferably is smaller than the effective area of the diaphragm 32, and the spring 62 is preferably of a comparatively low Arate so that its 'force can be overcome during deceleration conditions as will be explained hereinafter.

The throttle body 15 comprises'an air horn or casing 70 attached to the air-intake manifold 39, a large air throttle valve 71 and a small air throttle valve 72. The small air throttle valve 72 is disposed in a parallel air passage73 formed within the casing 70 and is the primary control valve lfor regulating the amount of air entering the air-intake manifold 39. The valve 71 normally opens after the valve 72 is open a substantial amount. The port 48 is formed in the casing 70 at a point immediately adjacent the upper or upstream side of the throttle valve 72. When the throttle valve 72 is closed, the port 48is subject to atmospheric pressure and when the valve is opened, the edge of the throttle valve blade passes beyond the port iS-so that the pressure developed at that point is substantially the same as the pressure within'the air-intake manifold 39.

Operation The control system 10 functions to meter the output of the pump llas follows:

When the engine is running, the pressure withinthe airintakemanifold 39 is less than atmospheric pressure and this pressure is transmitted through the conduit 37 to the control means 13. A differential in pressure between manifold pressure and atmospheric pressure is developed across the diaphragm 32. The force due to this .differential .in pressure tends to force the connecting shaft 24 and cam to the left, asshown, against the action of the spring 34 and thereby tends to reduce the output of the fuel injection pump 11. The differential in pressure is determined by the speed of theengine and 'therdegree of theopening of the throttle valves 72 and 71.

During idle conditions, both of the throttle valves 71 and 72 are substantially closed, the pressure within the air-intake manifold 39 is comparatively low, and the force due tothe differential in pressure across the eiective @H area of diaphragm 32 is comparatively large. The cam 20, therefore, is moved to the left tending to reduce the output of the pump 11.

As indicated above, it is necessary to enrich the fuel output during idle condition to compensate for exhaust gas dilution. The need for this enrichment is indicated by the graph of FIG. 4 which is a plot of the air-fuel ratio demanded Vby a fuel injection engine as a function of effective throttle opening. The upper curve on the graph shows the air-fuel ratio demand of a multi-cylinder engine with poor distribution, and the air-fuel ratio required at idle is indicated by the letter A. The lower curve shows the air-fuel demand of an ideal multi-cylinder engine. The demand of an engine .equipped with fuel injection approaches the ideal because of its superior distribution. However, even for the ideal engine, considerable enrichment at idle is required, as indicated at A', because of exhaust gas dilution.

A bias force to produce the necessary enrichment during idle condition is provided by the control means 14. The bias force is developed by the spring 62, and a reaction base for the spning 62 is established by a pressure differential developed across the area of the diaphragm 42. Manifold pressure is applied through the control means 13 to the right side of the diaphragm 42. Atmospheric pressure is applied at closed throttle condition through the port 48 and conduit 47 to the left side of the diaphragm 42. The differential vbetween atmospheric pressure and manifold pressure tends Vto force the diaphragm 42 and plunger 43 to the right until the flange 52 abuts against the shoulder 53. The end of the plunger 43 contacts the head of the screw 35 and exerts a bias force through the connecting shaft 24 on the camv 26. The plunger 43 is free to slide axially through the bore 51 against the action of the spring 62. The magnitude of the bias force so exerted, therefore, is determined by the calibration of the spring 62.

When the throttle valve 72is opened, the blade of the valve opens past the port 48, the pressure in the conduit 47 becomes substantially equal to the pressure within the air-intake manifold 39, and the differential in pressure across the diaphragm 42 drops -to Zero. The reaction base for the spring 62 is thereby removed and the diaphragm 42 and plunger 43 are permitted to iloat freely without exerting any force on the cam 20. This condition persists until the throttle valve 72 is again closed.

The spring rate of the spring 62 is comparatively low so that the bias force can be overcome during deceleration. In addition, the diaphragm 42 is preferably of a smaller eifective area than the diaphragm 32 so that the control means 14 is incapable of developing as much force as that developed by the control means 13.

During deceleration, both valves 71 and 72 are closed, and since the speed of the engine is normally greater than at idle speed, the pressure within the control means 13 and the air-intake manifold 39 is less than at idle condition. For deceleration condition, therefore, the force developed across the diaphragm 32 is sufficient to move the cam 20 and connecting shaft 24 to the left against the action of the spring 34 and servomotor 14 for leaning out or reducing the output of the pump 11. Since enrichment is desired during idle but not during deceleration, it is important that the control means 13 be elective to overcome the bias force of the control means 14 during deceleration.

There has been provided by this invention an improved control mechanism for a fuel injection pump that is effective to increase or enrich the output of the pump during idle condition, that is .overcome during deceleration conditions, and that is completely ineffective during open throttle condition.

It is to be understood that the invention is not to be limited to the specific constructions and arrangements Vshown and described, except only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. In a control mechanism for a fuel metering device adapted to supply fuel to an internal combustion engine having an air-intake manifold and an airthrottle valve for controlling the flow of air into the manifold, the combination of a movable cam connected to the metering device for controlling the fuel output thereof, a manifold pressure responsive control means connected to said cam and adapted to move it in response to changes in manifold pressure, and an idle control means comprising a flexible diaphragm and a plunger carried by said diaphragm and adapted to exer-t a limited bias force on said cam, said plunger carrying resilient adjusting means for calibrating the amount of bias force to be exerted thereby, and said idle control means being operably connected by means of a conduit to a port adjacent the air-throttle valve and responsive to pressure determined by the position of the throttle valve for exerting the bias force during closed throttle condition.

2. In a control mechanism for a fuel injection pump adapted to supply fuel to an internal combustion engine having an air-intake manifold and an air-throttle valve for controlling the admission of air into the manifold, the combination of a movable element connected tothe pump for controlling its output; a manifold pressure responsive control means connected to said element and adapted to move it in response to changes in manifold pressure; and an idle control means adapted to exert a limited force on said element during closed throttle condition, said idle control means comprising a casing, a exible diaphragm mounted in said casing, an adjustable plunger carried by said diaphragm, and resilient adjusting means carried by said plunger for calibrating the amount of force to be exerted by the idle control means, a conduit connected to said idle control means and to a port in the air-intake manifold for applying manifold pressure to one side of said diaphragm, and a second conduit connected to said idle control means and to a port adjacent the air-throttle valve for exerting a different pressure on the other side of said diaphragm, the different pressure becoming substantially equal to manifold pressure upon opening of said throttle valve.

3. In a control mechanism for a fuel injection pump adapted to supply fuel to an internal combustion engine having an air-intake manifold and an air-throttle valve for controlling the admission of air into the manifold, the combination of a movable cam connected to the pump for controlling its output, `a hollow casing, a ilexible diaphragm mounted in the casing, a collar carried by said diaphragm, an adjustable plunger slidably disposed within said diaphragm and adapted to exert a limited force Aon said cam, adjustable resilient means carried by said plunger for calibrating the amount of force to be exerted thereby, means including a first conduit connected to said casing and to a port in the air-intake manifold for applying manifold pressure to one side of said diaphragm, and means including a second conduit connected to said casing, a port adjacent and upstream from the air-throttle valve for applying a different pressure on the other side of said diaphragm, whereby the pressure differential between manifold pressure and said different pressure is effective on said diaphragm to provide a reaction base for said plunger during closed throttle condition and the pressure differential becoming substantially zero upon opening of said throttle valve past said second port.

References Cited in the file of this patent UNTED STATES PATENTS 1,960,432 Barker et al May 29, 1934 2,562,656 Blakeslee July 3l, 1951 2,798,469 Helmschrott et al July 9, 1957 2,808,819 Hagele et al Oct. 8, 1957 2,891,784 Taylor June 23, 1959 2,894,735 Zupanic July 14, 1959 2,908,491 Suozzo Oct. 13, 1959 2,984,467 Cedarholm May 16, 1961 3,064,636 Dahl NOV. 20, 1962 

1. IN A CONTROL MECHANISM FOR A FUEL METERING DEVICE ADAPTED TO SUPPLY FUEL TO AN INTERNAL COMBUSTION ENGINE HAVING AN AIR-INTAKE MANIFOLD AND AN AIR-THROTTLE VALVE FOR CONTROLLING THE FLOW OF AIR INTO THE MANIFOLD, THE COMBINATION OF A MOVABLE CAM CONNECTED TO THE METERING DEVICE FOR CONTROLLING THE FUEL OUTPUT THEREOF, A MANIFOLD PRESSURE RESPONSIVE CONTROL MEANS CONNECTED TO SAID CAM AND ADAPTED TO MOVE IT IN RESPONSE TO CHANGES IN MANIFOLD PRESSURE, AND AN IDLE CONTROL MEANS COMPRISING A FLEXIBLE DIAPHRAGM AND A PLUNGER CARRIED BY SAID DIAPHRAGM AND ADAPTED TO EXERT A LIMITED BIAS FORCE ON SAID CAM, SAID PLUNGER CARRYING RESILIENT ADJUSTING MEANS FOR CALIBRATIN 